Apparatus for proportionately mixing air and gas



Feb. 16 1926. n 1,573,079

G. w. MCKEE APPARATUSFOR PROPORTIONATELY MIXING AIR AND GAS Filed April16, 1924 Patented Feb. 16, 1926.

UNITED STATES PATENT OFFICE.

GARNET W. IlllIoKEE, 0F ROCKFORD, ILLINOIS.

Application iled April 16, 1924. Serial No. 707,010.

certain new and useful Improvements in` Apparatus for ProportionatelyMixing Air and Gas, of which the following 1s a specification.

This invention relatesin general to apparatus for mixing air and gas andpertains more specifically to apparatus of this character adapted todeliver air and gas in predetermined proportions irrespective ofvariations in the air flow induced by a variable resistance in theairline or by other causes.

In gas ired furnaces and other apparatus of similar character it isfrequently desirable for purposes of economy and e ciency to pass theair constituent of the combustible mixture delivered to the burners,through a recuperator or other apparatus by which heat units from theexhaust gas of the furnace are transferred to the intlowing air. Sincethe inflowing air passing through the recuperator is expanded to agreater or less degree, depending upon the temperature of the exhaustgases from the furnace, it follows that the recuperator acts as avariable resistance to the How of air through the air line.

The primary purpose of my present invention is to provide a proportionalmixing apparatus which will deliver a mixture of air and gas of properproportions irrespective of fluctuations in the pressure of the air andgas constituents and irrespective of variations in the resistanceimposed upon the air line beyond the control point.

Another object is the provision of an apparatus of the characterindicated which will be very sensitive to How variations in the airline, one which will be thoroughly reliable in operation, and one inwhich the volume of mixture maybe controlled by the manipulation of asingle valve in the air line.

Another object is to provide an apparatus which will be readily capableof adjustment so as to vary the relative proportions of air and gasdelivered in order to produce a combustible mixture of the requisite proportions.

My invention further contemplates a novel method by which the desirablecharacteristicsabove mentioned, and others, may be secured. 1

Otherpobjects and advantages' of my invention should be readilyappreciated as the same becomes better understood by lreference to thefollowing description, when considered in connection with theaccompanying drawing.

vOn the drawing,-

The single gure is a somewhat diagrammatic side elevation, partially insection, of an apparatus constructed in accordance with my invention.

Referring to the drawing more in detail, reference character 5 indicatesgenerally a fragment of the side wall of a furnace or other heating aparatus into which the delivery nip le 6 o a mixing burner indicatedgenerally y 7 projects. While this mixing burner may be of any preferredconstruction, it is illustrated as being of the type wherein the air andgas enter the burner casing from opposite sides and are de livered intothev nipple in a series of concentric rings or cylinders of differentdiameters, the rings of air alternating with the rings of gas as iscommon in this type of burner.

Gas is supplied to the burner through a gas supply pipe 8 in which isinterposed a control device indicated generally by 9 and commerciallyknown as a zero regulator. The regulator comprises a balanced valve 11suspended from an adjustable spring 12 and connected with a diaphragm13, the lower face of which communicates through a port 14 with thedelivery chamber 15 of the casing and the upper face of which issubjected to air pressure entering through an intermediate pipe 16 andcontrolled as will be later explained.

Air is supplied under pressure to the burner through an air supply pipe17 in which is interposed a recuperator 18 or other apparatus adapted toproduce a varable resistance in the air line. Since the recuperator orother apparatus may be of any well known or preferred type, the detailsof construction thereof are not illustrated herein but the apparatus isdiagrammatically illustrated only.

The point in the air line to which the gas control is connected islocated forwardly of the recuperator, that is, between the recuperatorand the fan blower or other apparatus cn'lployed for delivering airthrough the llille under pressure.

Since the flow of air through the air line will vary in accordance withvariations in the. resistance imposed upon the line by the recuperator,m present invention contem-4 plates the utilization of this variation 1n flow to control the delivery of gas to the burner in accordance withthese air vflow wu'iations. vWith this end in view I have im terposed inthe air line a Venturi tube 1 9 and have connccted'a pipe 21 to saidtube near its intake end and a pipe 22 to the throat of the tube. Sincethe volume of air flowing through the tube is-a .square root function ofthe difference in pressures exerted on the pipes 21 and 22 from thet-ube, it will be manifest that through these pipe connections with thetube I obtain a pres-l sure differential which may be utilized forcontrolling the gas.-

The pipes 21 and 22 are connected to ya diaphragm chamber 23respectively above and below a diaphragm24 disposed therein. Thischamber and diaphragm are part of a control unit indicated generally by25, comprising also a second dia )hragm chamber 26 in which a diaphragm2 is mounted, the chamber above the diaphragm being open to atmospherethrough a port 28 and the chamber below the diaphragm communiveatingthrough a port 29 with the delivery chamber 31 of a casing to which theair line 17 is connected through a branch. 32. A balanced valve 33 susended from an adjustable spring 34 an connected with the diaphragms 24and 27 regulates the .air pressure entering the chamber 31.` Since thepressures exerted through the pipes 21 and 22 upon the upper and lowerfaces .of the diaphragm 24 vary in conformity with variations in airflow through the venturi 19 the valve 33 connected to the diaphragm bythe rod 2O will be correspondingly opened or closed, thus varying theair pressure in the chamber 31 in accordance with variaclude thedelivery of an excessive air pres-- sure through the pipe 16arestriction 34 is interposed in the connection between 'the pipe 16 andthe chamber 31. Furthermore,

.in order to variably reduce the pressure transmitted to the controller'9 so that the f movements of the valve 11 inthe gas line,

lthrough the venturi.

delicate control, I have intel osed in the connection between the controer 9 and the chamber 31 of the main controller anl adj ustable deliveorifice 35 throu h which communication etween the interior ofthe pipe 16and atmosphere'is established. e. This orifice may be manually regulatedto per'mitthe escape of anydesired proportion of the air pressuredelivered to the connecting pipe 1.6. Consequently by regulating thisorifice any desired fraction of the air pressure lating valve 36 orother preferred means of 4 control. The ratio of gas delivered in pro--portion to this maximum of air may be regulated by the hand valve 37 inthe gas line 8. When the desired ratio' has been estabnecting 37 and 7may be considered as one and the same resistance and this' compositeresistance can be varied by manipulating the valve 37. A

Now the amount of gas flowing from v15 to the furnace varies as thesquare root of the difference in ressure between point 15 and thepressure 1n the furnace. Since the pressure in the furnace is verylow-substantially atmospheric pressure-the quantity of gas flowing tothe furnace varies as the square root of the pressure at l5. Likewisethe flow of air through the .venturi will be a corresponding function ofthe difference in pressure between the intake end and the throat of theventuri. This ressure difference is transmitted through t e pipes 21 and22 to the diaphragm 24 which controls the valve 33 so that the pressurein the chamber 31 becomes also a function of the quantity of air flowingthrough the venturi. This pressure or such fraction thereof as may bedetermined by the adjustable ori fice 35 is transmitted to the gascontroller 9 with the result that the pressure of the gas at the outletof the controller is likewise a function of the volume of air flowingThe pressure on the inlet side of valve 37 varies, therefore, inaccordance with variations inthe quantity of air flowing through theventuri, consequently the quantity of gas delivered past -this valvewill always bear a simple ratio to the quantity of air delivered andthis ratio may be varied by adjusting the valve v37. The predeterminedproportions of air and gas in the mixture will., therefore, always bemaintained irrespective of variations in the quantity of air delivered.

The structural details illustrated and described may obviously be variedwithin considerable limits without departing from the essence of theinvention as defined in the following claims.

I claim:

l. In'` an apparatus for proportionately mixing air and gas, an airv.supply line, means for producing apressure difere'ntial in said airline, an intermediate pipe, means for varying the iuid pressure in saidpipe in' accordance with said diiierential, a gas supply line, andmeansfor varying the i'low of gas in said gas supply line in accordance withthe pressure in said pipe.

2. In an apparatus for proportionately mixing air and gas, an air supplyline, means for producing a pressure differential in said air line, anintermediate pipe, adjustable means for varying the pressure in sai-dpipe in accordance with said differential, a gas supply line, andadjustable means for varying the flow of gas in' said gas supply line inaccordance with the pressure in said pipe.'

3. In an apparatus forl proportionately mixing air ,and gas, an airsupply line, means for producing a pressure differential in said airline, an intermediate pipe, adjustable means for varying the pressure insaid pipe in accordance: with said diierential, a gas supply line,adjustable means for varying the'ow of gas in the gas supply line inaccordance with the pressure in said pipe, and adjustable means forstopping the ow of gas in said gas supply line when the pressuredifferential in Vthe air line decreases below a predetermined value. v4. In an apparatusv for proportionately mixing air and gas, thecombination of an air supply line, a gas supply line, a controller insaid gas supply line, means in said air supply line for producing apressure differential adaptedl to fluctuate in accordance withfluctuations with the flowin said line, a branch line connecting saidair supply line with said gas' controller, and means controlled throughsaid pressure differential for regulating said gas controller throughthe intermediary of the air lin said branch line.

' 5. In an apparatus for proportionately mixing air and gas, thecombination of an air supply line, a gas su ply line, a gas con,-troller in said gasl supp y line, a connecting pipe between fiid airsupply line and said controller, and means controlled by the low of Iairin said air supply line for regulating said gas controller through theintermediary' of the air in said connecting pi e to thereby regulate theflow of gas in sai -gas Asupply line in accordancev with variations ofiow in the air supply line.

6. In an apparatus for proportionately mixing air and gas, thecombination of an air supply line, a gas supply line, a controller insaid gas supply line, a connection between the air supply line and thecontroller,

, a regulating valve in said connection, means in the. air supply linefor producing a pressure differential in accordance' with variations inthe flow through said line, and means actuated by said pressuredifferential for controlling said regulating valve.

7. In an apparatus for proportionately mining air and gas, thecombination of an Iair supply line, a gas supply line, a gas flow'controller in said line, said controller including a diaphragmcontrolled valve, an air connectinr pipe between said air line and saiddiap ragmta regulating valve in said `air connecting pipe, a Venturitube'in said air supply line, .a diaphragm connected with saidregulating valve, and means for stablishing communication betweenopposite faces of said diaphragm and the intake end ang the throat,respectively, of said Venturi tu e. y

48. In an apparatus for proportionately mixing air and gas, thecombination of an air' supply line, a gas supply line,a gas flowcontroller in said gas supply line, comprising a diaphram controlledvalve, a pipe establishing communication between the air supply line andone face of the diaphragm of said controller, a regulating valve in saidpipe, the diaphragm controlling said valve,

a Venturi tube in the air supply line, a pipe connecting an end of saidtube with one face of said diaphragm, a pipe connecting the throat ofsaid tube with the other face of the diaphragm, and a Variableresistance device interposed in the air supply line at the delivery7side of said Venturi tube.

9. In an apparatus for proportionately mixing air and gas, thecombination of an air supplyline, a gas supply line, a gas flowcontroller comprising a diaphragm controlled valve in the gas supplyline, a recu perator in the air supply line, a Venturi tube 1n the airsupply line ahead of the recuperator, a pipe connecting the air supplyline with said gas controller,` a primary controller comprising a doublediaphragm. controlled valve interposed in said pipe, an adjustableorifice in the pipe `between the said controllers, means forestablishing communication between one end of the venturi and one faceofthe diaphragm with the primary control- 1er and means for establishingcommunicationbetween the throat of said venturi and the other face ofsaid diaphragm.

'p f GARNET W. MCKEE.

